Sheet materials such as drywall are commonly used for wall cladding in the construction of building and houses. These sheet materials are usually supplied in selected sizes, such as 4 feet.times.8 feet. When installing these sheets it is often necessary to cut strips of uniform width and this is generally accomplished by using a knife, such as a utility knife, in conjunction with a measuring tape. The end of the tape measure is held against the side of the utility knife with the thumb and the tape is extended across the sheet to the a desired width, holding the tape reel against the edge of the sheet. With the tape reel or casing held in one hand and the knife in the other, both hands are moved down the sheet simultaneously such that the knife scores a line parallel to the edge of the sheet. The final cut is then made without the tape measure by using the knife along the scored line. The sheet is subsequently bent along the scored and cut line until it breaks, resulting in a strip of the desired width.
Generally, it is not feasible to apply sufficient pressure to the knife to make the required cut in one pass across the sheet when using the above described method. Also, problems are frequently encountered when simultaneously measuring and cutting in the manner described above, such as for example, slippage of the cutting blade or inaccurate cutting or scoring. These problems can result in wasted time and materials thus adding to the construction cost.
The problems described above are well known in the art and various devices and methods have been designed by others attempting to solve these problems. For example, U.S. Pat. No. 5,206,965 (Rowley, 1993) discloses a knife having a housing with a thumb positioning structure associated with elongated sides. A measurement means is held in place against the thumb positioning structure by the user's thumb. U.S. Pat. No. 4,993,093 (Goldwitz, 1991 ) discloses a utility knife having an elongated slot extending in the same plane as the cutting blade. The angled tip of a flexible ruler is retained within the elongated slot. U.S. Pat. No. 4,949,462 (Spencer, 1990) discloses a drywall device which includes a sleeve for slidably mounting on a stem of a T-square. A clamping device is mounted on the sleeve for retaining the sleeve on the T-square. A knife holder containing a knife is joined with the sleeve of the '462 patent. U.S. Pat. No. 4,903,409 (Kaplan et al., 1990) discloses a drywall scribing and scoring tool which includes a knife holding unit and scribe units for attachment along an arm of a T-square. U.S. Pat. No. 4,255,856 (Mackie, 1981 ) discloses a utility knife having an attachment which permits the tape of a tape measure to be directly coupled to the knife. U.S. Pat. No. 2,952,025 (Johnson, 1960) discloses a knife which includes a reel containing a measuring tape and a guide structure at the outer end of the tape.
Known cutting devices, as exemplified by the above referenced patents, do not provide an optimal design combining ease of use, cutting accuracy, and small size. For example, the cutting devices described in the '965, '093, '856 and '025 patents utilize knives generally known as utility knives where the user holds a knife handle. When using such a utility knife, force is applied to the knife blade mainly by the user's wrist since the knife handle is held in the palm of the user's hand while the blade extends from the handle. In other words, the user is generally unable to push down directly on the cutting tip of the knife blade. Such placement of a cutting knife as an extension of a hand held handle may result in cutting inaccuracies because the user may twist or turn the handle while scoring or cutting the sheet.
The '462 and '409 patents utilize T-squares. It is well known to those skilled in the art that the users of drywall cutting devices prefer that these devices are small to easily fit in a user's pocket or tool belt, enabling the user to move unencumbered on a construction job site. T-squares for use with drywall cutting devices commonly have a relatively long arm or stem thus not fitting in the user's pocket and generally unsuitable for a tool belt.
Accordingly, the need exists for a drywall cutting device having improved ease of use and improved cutting accuracy.